Adults, families and kids. Register children and adults; children must be accompanied by a registered adult. The City Nature Challenge 2018 includes over 75 cities on six continents, in a contest to see who has the most nature and the most engaged citizen scientists. Learn the basics of using iNaturalist, the app for this challenge. Then go out into Gulf Branch Natural Area in search of nature observations to contribute. This is the first day of a four-day challenge, so you can use what you learn today to contribute over the whole weekend! For information: 703-228-3403. Meet at Gulf Branch Nature Center. Registration Required: Resident registration begins at 8:00am on 2/13/2018. Non-resident registration begins at 8:00am on 2/14/2018.